1. Field of the Invention
The present invention relates to an optometric apparatus and an optometric measurement method that automatically aligns with an eye to be measured, by driving a drive means in accordance with position information from a position detecting means.
2. Description of the Related Art
Known optometric apparatuses include position detecting means for detecting the position of an eye to be measured, and drive means for moving the apparatus in any direction, upward or downward, rightward or leftward, and forward or backward. Such an optometric apparatus automatically aligns with the eye of a subject by driving the drive means in accordance with position information from the position detecting means. When an operator presses a measurement switch, the apparatus measures a relative position of the eye to be measured and the apparatus, and part of the apparatus moves so that the apparatus aligns with the position of the eye to be measured. When a positional error between the eye and the apparatus falls within a predetermined permissible range, an optometric measurement is initiated.
When the measurement of the one eye is completed, an optometric unit of the apparatus is shifted by the human interpupillary distance of a subject (the average human interpupillary distance is about 60 mm) in response to an input from a left-right changeover switch. Since the eye and the apparatus are, occasionally, not accurately aligned, a manual operation is further performed for alignment before pressing the measurement switch.
In the above conventional art, the operator is required to align further to some degree each time the apparatus is shifted from one to the other eye. When the operator is busy handling a plurality of optometric apparatuses at the same time, attending to the apparatus each time for the left-right switching is troublesome. When subjects themselves perform optometric measurement, they are required to move themselves so that their eyes fall within an alignment detection range when the shifting to the other eye is performed. A manual operation to put the apparatus to within an automatic alignment detection range needs a device such as a joystick or trackball.